Modular EGR Mixer With Convergent-Divergent Nozzles for Low-Pressure Delivery
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Solution Overview
Problem
Existing exhaust gas recirculation (EGR) systems face challenges in delivering cooled EGR to internal combustion engines without negatively impacting engine efficiency and increasing knock tendency, particularly in high efficiency engines where the exhaust manifold pressure is lower than the intake manifold pressure.
Innovation Solution
An EGR mixer system with a convergent-divergent nozzle configuration and a jet pump mechanism that utilizes a pressure differential to facilitate the flow of exhaust gas from the exhaust manifold to the intake manifold, combining air, exhaust gas, and fuel streams to create a well-mixed combustible mixture, enhancing engine efficiency and reducing knock tendency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the classic high pressure loop cEGR system plumbs exhaust gas directly to the intake manifold, then exhaust gas recirculation is achieved, but engine efficiency is reduced due to negative pressure work and residual gas retention
Solution Approach 1:
A low-pressure receiver chamber is introduced as an intermediary between the exhaust manifold and intake manifold. This receiver acts as a buffer that decouples the pressure differential requirement from the EGR delivery, allowing exhaust gas to be transferred without creating negative pressure work on the engine cycle.
Solution Approach 2:
The EGR system is segmented into distinct pressure zones: a high-pressure exhaust manifold, a low-pressure receiver chamber, and an intake manifold. This segmentation allows each component to operate at its optimal pressure, with the receiver serving as a pressure transition zone that prevents efficiency losses.
2Quantity of substance
If design or variable turbocharging is used to force exhaust manifold pressure higher than intake manifold pressure, then cEGR delivery is enabled, but scavenging of hot burned gases is reduced and engine P-V cycle efficiency is lost
Solution Approach 1:
The receiver chamber is designed to maintain pressure equipotential conditions that favor scavenging. By keeping the receiver at low pressure (lower than or equal to intake manifold pressure), the system maintains favorable pressure-volume pumping loop work that promotes efficient scavenging of hot burned gases from the cylinder.
3Loss of energy
If cEGR is delivered from exhaust manifold to intake manifold without pressure differential, then engine efficiency is maintained, but cEGR delivery becomes challenging when exhaust manifold pressure is lower than intake manifold pressure
Solution Approach 1:
The low-pressure receiver serves as a mediator that enables cEGR delivery even when exhaust manifold pressure is lower than intake manifold pressure. The receiver accumulates exhaust gas at low pressure, and when intake manifold pressure drops or exhaust pressure rises, the accumulated EGR is delivered to the intake manifold without requiring active pumping.
4Adaptability or versatility
If the convergent nozzle accelerates air flow to high velocity, then mixing with exhaust gas is enhanced, but pressure differential requirements increase
Solution Approach 1:
The convergent nozzle utilizes the existing pressure differential between the low-pressure receiver and the intake manifold to accelerate air flow and enhance mixing. The system is designed so that the pressure conditions naturally provide the driving force for the convergent nozzle, eliminating the need for additional energy input or active pumping.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively recirculates exhaust gas while maintaining engine efficiency and reducing knock tendency by leveraging the reverse Bernoulli Effect to equalize manifold pressures, improving power output and reducing parasitic losses.
Implementation Method 1
The convergent nozzle accelerates the flow to high velocity, which is released as a free-jet
Implementation Method 2
The mixer includes an exhaust gas housing having an exhaust gas inlet into an interior of the exhaust gas housing, and a convergent-divergent nozzle having an air-fuel-exhaust gas inlet in fluid communication to receive fluid flow from the convergent nozzle
Data Source
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AI summary
A modular exhaust gas recirculation mixer system comprising: an exhaust gas housing comprising an exhaust gas inlet (212) into an interior (228) of the exhaust gas housing; a mixer housing (210); a convergent nozzle module (202) received in the mixer housing and in a flow path from an air inlet (204) of the mixer to an outlet (206) of the mixer, the convergent nozzle converging toward the outlet of the mixer; a convergent-divergent nozzle module (214) received in the mixer housing and comprising an air-exhaust gas inlet (230) in fluid communication to receive fluid flow from the convergent nozzle and from the interior of the exhaust gas housing;